Global Warning

In this desert, no living thing moves. Rocks and saguaro cactus bake on the barren hills. The sun is so bright that it hurts to look at it--even on a television screen.

A voice, British and full of Shakespearean portent, rolls over the scene. "It has all the hallmarks of a good disaster movie," the voice warns. "An impending crisis that threatens to engulf the world. From an almost benign start, a hardly perceptible change in global temperature, the Earth could suddenly topple into crisis...large tracts of land to desert...wreaking havoc on our culture."

A clean-cut young man--the narrator--wanders out onto the desert, hands in his pockets. "Nor is it a theory supported by a few cranks," he says. "It's been endorsed by the great and the good, by politicians and academics. There's only one problem."

The Greenhouse Conspiracy was not a hit when Mickey Glantz, a political scientist at the National Center for Atmospheric Research in Boulder, showed it to his NCAR colleagues. Although the film makes several valid points about the scientific uncertainty surrounding the so-called "greenhouse effect," there's no mistaking its basic message: Man's contribution to global warming is a myth.

Conspiracy, which Glantz says was produced by the coal industry, features cameos of scientists patronizingly dismissing the threat. And the narrator goes on to ambush other scientists who support the scenario that man contributed to global warming, including Stephen Schneider, the eminently quotable and controversial former head of climate research at NCAR.

At the end of the showing, Glantz asked the NCAR researchers for their comments. But he wasn't as interested in their opinions of the film's science as he was in their reactions to Conspiracy's politics.

And they reacted angrily--not just to the film, but also to the messenger who'd brought it to them. "They wanted to know why I would show it at NCAR," he says. "Why give it any publicity?"

When Glantz showed The Greenhouse Conspiracy to the NCAR researchers' counterparts at Colorado State University's Department of Atmospheric Sciences, however, the CSU scientists supported the film's assertions--and Glantz's right to show it.

These days, the hottest thing about global warming is the rhetoric it inspires. That bothers Glantz. While he personally believes evidence is "leaning toward" man having contributed to global warming, he cautions that this belief is not yet a proven fact. Other scientists, like those at CSU, are far more cautious and warn that global warming may ultimately prove a false alarm. But in the meantime, he says, the theory's stalwart proponents are bypassing the peer review system that has been the hallmark of American science and moving full speed ahead--straight into the political arena.

The scientific schism is deep, and it cuts close to home. Both NCAR and CSU's atmospheric-sciences department are respected institutions, staffed by researchers with international reputations. Throw in the National Oceanic and Atmospheric Administration (NOAA) lab in Boulder, and the Front Range boasts a leading brain trust on weather.

Yet when these brains storm, they do not agree.
NCAR scientists generally align themselves with the camp that believes man's contribution to climate change, through the production of greenhouse gases--carbon dioxide, methane and water vapor--is both detectable and a cause for serious attempts at mitigation, if not outright alarm. NCAR researchers frequently make public pronouncements on the issue, sitting on presidential commissions and serving as major participants in the U.N.-sponsored International Panel on Climate Change (IPCC), which in 1995 released a proclamation that man had made a "discernible impact" on the climate of his home planet.

The CSU researchers are more likely to work quietly in their labs than to sound off publicly. They're counting on science to ultimately show whether man's contribution to global warming is a real threat or whether climate change can be attributed to purely natural causes.

In December, IPCC representatives from most of the world's countries will be meeting in Kyoto, Japan, to draft a treaty that would reduce greenhouse gases by limiting the burning of fossil fuels by industrialized nations. President Bill Clinton has already announced that the United States will make such a commitment; the Republican-controlled Senate, however, has warned against agreeing to anything that would seriously harm the U.S. economy.

Both sides of the global-warming debate--locally, nationally and internationally--charge each other with selling their science for money. Both sides accuse each other of using scare tactics: predictions of global catastrophe on one hand, economic ruin on the other. And both sides claim that they're in the majority.

"They're forty miles apart," Glantz says of the NCAR and CSU scientists. "They all have Ph.D.s. They all read the same science. But in some cases, they won't even talk to each other...You have to ask: What is happening to science?"

Good question.

The National Center for Atmospheric Research sits high above Boulder on a mesa, fulfilling the dream of its founder, Walter Orr Roberts, that NCAR scientists "see human civilization below, the mountain wilderness behind, and the ever-changing skies" as they try to understand the connections between them.

No ivory tower, the facility is a pinkish sandstone structure designed to echo the Mesa Verde ruins. A narrow road snakes its way up from the valley below, past a sign proclaiming that NCAR is "sponsored by the National Science Foundation," to a park-like setting of natural grasses and widely spaced conifers nestled up against the Flatirons. A "weather trail," open to the public, winds off behind the complex where deer and Lycra-clad joggers play.

In the lobby of the main building, tourists hailing from California to Korea wait for their tour to begin; a toddler wearing a T-shirt bearing the slogan "I love my planet" wanders among them. The tour guide, a friendly young man named Tom, begins his spiel by informing the group that if they came to see the Atomic Clock, they're going to have to go back down the road to the National Institute for Standards and Technology. NCAR, he says, studies weather and climate. And climate, he explains, is the average weather of a region, affecting such things as where, and how successfully, crops can be grown. Then, with Tom in the lead, the tour sets off to view a variety of displays concerning subjects being researched by this center's scientists who, Tom says, are doing their thing elsewhere in the building.

Lightning...tornadoes...hail...all aspects of Mother Nature at her worst are represented here. But through their "applications program," Tom says, NCAR scientists are working to mitigate bad weather. For example, NCAR developed an apparatus to detect microbursts near airports. Microbursts, of course, "can cause an airplane to make premature contact with the ground," Tom notes with a smile. When the chuckles die down, he adds, "We also were asked to look into microburst activity out east when they were planning DIA."

"How did it compare to Stapleton?" asks a man who flew in from South Dakota.
"At least as much and probably stronger," Tom replies. "They took our findings into consideration...and built it there anyway." He smiles again, and everyone laughs except the guy who asked the question. He looks worried.

People worry a lot about things over which they have no control, like the weather. And politicians, who presumably have some control over something, don't always listen to the advice of scientists.

The group wanders past an "obsolete" Cray Supercomputer--purchased in 1963 for $15 million--and heads to the second-floor foyer, which is decorated on one side with paintings by local artists and on the other with a variety of photographs of the sun. At the far end is a display dedicated to an area of research for which NCAR is often in the news these days: climate change and global modeling. Of NCAR's $98 million budget, $63 million comes from the National Science Foundation, which gets its money from the federal government; the rest comes from other government agencies, such as NASA and the FAA, and non-government sources.

This exhibit includes an illustration of the "potential" global-warming pattern for the year 2050 A.D. based on computer projections, or modeling--an NCAR specialty. The text accompanying the graphic concedes that the models cannot "exactly predict" climate for specific regions but "can give a reasonable estimate." Humans, the panel continues, are adding an "uncertain element" to global warming. But despite this uncertainty, the NCAR display asserts--with an unequivocable assurance that drives global-warming "naysayers" up the wall--that there will be an increase in global temperatures of 6 to 10 degrees Fahrenheit over the next fifty years. Such an increase, it warns, could mean rising sea levels, unpredictable droughts and floods, and the extinction of some plant and animal species.

A older woman looks at the panel and shudders. "Oh, 2050," she says to her husband. "Glad I won't be here."

The Earth's temperature has always fluctuated. The most obvious examples are the Ice Ages, periods of cool temperatures when much of the world was covered by glaciers, which were followed by warmer periods when the glaciers retreated. It's been 10,000 years or so since the last major Ice Age, known as the Pleistocene Epoch, when average temperatures were 5 to 9 degrees cooler than today. Since then, however, the world has experienced a series of less dramatic global warmings and chillings.

About 6,000 years ago, during the Holocene Maximum, when the great civilizations of Mesopotamia and Egypt were flourishing, the Earth was an estimated 2 degrees Fahrenheit warmer, and wetter, than it is now. Hippos and crocodiles lived in what today is the bone-dry Sahara.

By 1400, the world on average had cooled to temperatures comparable to those of today. But in the intervening centuries, it would cool even further into what is known as the Little Ice Age. "Little" in terms of the extent of global cooling, it had a major impact on humans.

The cold caused great cultural dislocation and strife. In the 1600s and 1700s, farms and villages in Europe were crushed by glaciers that crept down from the mountains as priests, who blamed the events on sinful people, asked God to intercede. At various times, ice choked the North Atlantic, ruining the fisheries in Scandinavia. Along the east coast of North America, northern tribes moved south to avoid the cooler weather and shortened growing seasons, coming into conflict with southern tribes. As late as the 1800s, New York Harbor froze so solid that people could walk from Manhattan to Staten Island.

The world finally began to emerge from the Little Ice Age sometime in the last half of the nineteenth century. It's been warming up, with fluctuations, ever since.

Scientists are confident that the Little Ice Age was a natural occurrence for the Earth, which tends to self-regulate itself over time. In fact, they say, a spike of high temperatures during the 1930s, when the Dust Bowl decimated mid-America, was most likely a planetary correction for a previous spate of cooling and had nothing to do with man--even though it occurred well into the Industrial Revolution.

The idea that humans might have an effect on climate--largely because of the release of greenhouse gases from the burning of fossil fuels such as coal and oil--was first proposed a century ago by Swedish chemist Svante August Arrhenius. But Arrhenius's theory was no cause for alarm; in fact, he suggested that pumping more carbon dioxide and methane into the atmosphere might be good, warding off future Ice Ages and extending growing seasons in temperate climes.

Arrhenius was never able to confirm his hypothesis. (Today, most scientists agree that man's contributions to naturally occurring greenhouse gases weren't significant enough a century ago to have made a measurable impact.) But since his time, whenever the world experienced a temperature or a chill, there was someone wondering what it presaged for the future of mankind.

In the 1970s, a few years of particularly cold winters and heavy snows convinced some scientists that we were entering another Ice Age of indeterminate size and duration. One of those scientists was Stephen Schneider, who warned of impending disaster due to global cooling: "I have cited many examples of recent climatic variability and repeated the warnings of several well-known climatologists that a cooling trend has set in...perhaps one akin to the Little Ice Age."

A few years later, however, Schneider, by now the head of climate research at NCAR, reversed his position and predicted that the Earth was headed for global disaster--because greenhouse gases were heating it. By the early Eighties, Schneider was a leading authority on global warming, sounding the alarm loudly and often.

Schneider defended his flip-flop by saying he'd been swayed by recent evidence and would have been less than honest if he'd clung to his previous ideas. Scientists advocating on behalf of environmental activism often find themselves in a "double ethical bind," he said, in a statement that still has his former NCAR colleagues rolling their eyes.

"We have to offer up scary scenarios, make simplified, dramatic statements and make little mention of any doubts we might have...Each of us has to decide what the right balance is between being effective and being honest."

Jerry Meehl leans back in a chair in his tiny, cramped NCAR office. At least he has a beautiful view of the mountains.

Since he grew up on a dryland wheat farm in eastern Colorado, it's no wonder Meehl made a career out of studying the weather. "It was all anybody talked about," he says. "I remember when the wheat was close to cutting time, we'd look at the clouds gathering to the west and worry about which ones had hail. We wanted the rain but hoped the hail would go around."

Meehl's father got out of farming when Jerry was still a boy, and the rest of his relatives have since retired. But at family gatherings, weather still dominates the conversation.

They're all tuned into current climate issues, Meehl says, like El Nino, a natural seasonal upswelling of warm sea currents in the Pacific thought to cause droughts in some areas, deluges in others. But after years of watching weather forecasters get it wrong, his relatives view science "with a great deal of skepticism," he adds. "They know there's a lot of uncertainty."

Meehl, who's thin and tan and looks like a farmer turned scientist, is used to dealing with uncertainty. One of NCAR's thirty or so computer climate modelers, he received his Ph.D. in climate studies from the University of Colorado in 1987 while working on a Department of Energy grant to study the effect of burning fossil fuels. "We can't run the real system forward in time," he says, stating the obvious, "so we used computers to do it for us."

Today those computers--and often Meehl himself--are at the center of the storm surrounding global warming.

The prediction that man's contribution to greenhouse gases will raise the average world temperature is based largely on computer models. Essentially, climate modelers take the factors that contribute to weather patterns--energy from the sun, precipitation, land and ocean temperatures--and build a mathematical model that re-creates global climate processes as closely as possible. The scientists then plug in a doubling of the amount of carbon dioxide, a greenhouse gas that traps heat, and let the computer project the future shock.

Computers have been used in weather forecasting since the 1950s, mostly to look ahead a few days. Even today, most "long-range" forecasts on television newscasts generally stick to five days, because that's how far you can predict a specific weather pattern (for instance, will a storm off the Pacific Northwest cause snow in Colorado a few days later?). "And despite what people think, they've gotten pretty good," says Meehl, adding that the modelers are also making progress in the area of seasonal forecasts.

It's the long, multi-decade predictions that spark heated controversy.
Meehl admits that climate modeling has limitations. The largest, perhaps, involves clouds, which computer modelers have not been able to fit into their equations with any assurance of accuracy. Although clouds usually have a cooling effect on temperatures, some types of clouds hold in heat. Under NCAR's global-warming scenario, increased heat would cause more evaporation, which would in turn create more clouds. But would those clouds have a net cooling or warming effect?

Another problem is that the current computers, as fast and powerful as they are, deal with generalities over a large land area. Data fed into the computer comes from grid points on a map, but the grids are so large that one over Oregon, for instance, would include (moving west to east) the coast, the coastal range, the Willamette Valley, the Cascades and the desert of the Great Basin--which have widely varying climates.

Critics of climate modeling note that without fudging the data, computers have been unable to recreate present climate patterns--much less accurately predict future patterns. Computer models from various institutions agree more with each other than they do with the real world, Meehl acknowledges; in other words, they tend to make the same errors. For example, computer models have been able to predict El Nino occurrences, but for some reason the predictions are smaller than the real thing by as much as one-third.

But technological progress is being made, Meehl adds. Recently, NCAR modelers were able to match computer models to present conditions without fiddling with data. While that's not yet predicting the future accurately--most modelers agree the computers are ten years from getting that right--it's a step closer.

"The way I view this is that climate modelers are giving their best estimate with the tools we have," Meehl says. "The policy-makers can take that information, along with twenty other pieces of evidence from other sources, and use it as a whole to make their decisions."

The best decision they could make regarding the threat of global warming, Meehl says, is to adopt what has become known as a "no-regrets policy." Rather than making massive, economy-shaking commitments to cut emissions quickly, the no-regrets strategy calls for smaller steps to wean ourselves from fossil fuels--which will run out sooner or later, whether or not global warming is a real danger. That means focusing on more energy-efficient cars and buildings, and emphasizing research and development of other energy sources.

Meehl blames policy-makers and the media for exaggerating the accuracy claims of computer models--and for fanning the flames of debate. "There is a real danger in overselling the science," he says. Although the U.S. government spent about $1.7 billion in 1997 alone on computer-model development, federal funding doesn't fuel the alarming predictions about global warming, he insists. "If, by perfecting the models, I can 'prove' what's going to happen in fifty years," he adds, "then I've solved the problem. And that would be the end of my funding."

And the government isn't the only entity funding research. The energy industry has also joined the fray, sponsoring a campaign of "disinformation and personal attacks" to discredit global-warming proponents, Meehl says, adding, "I don't think anybody on the science side anticipated the response of the energy industry."

When scientists accept money from the energy industry, he says, it's akin to scientists being "bought off" by the tobacco industry. Fortunately, he adds, "the majority don't get into the policy debate. We let the science speak for itself."

And Meehl doesn't need to look to his computer models to know that the science of climate and weather is an uncertain one. "I have a friend who's a farmer in Brighton," he says. "Last May, which was real dry, I asked him how his crops looked, and he said terrible.

"In June it rained a lot, and when I asked, he said they looked great...You just never know about the weather."

Forty miles to the north of the NCAR citadel, the building housing CSU's atmospheric-sciences department also sits on a hill--a rather plain little hill of dirt and grasses that overlooks a water-treatment plant and the wind tunnels of the engineering department. A half-mile to the west looms a manmade wall of rock that holds back the waters of Horsetooth Reservoir.

There is no user-friendly weather trail here, only a collection of satellite dishes--large and small--pointing toward the sky. The building itself is a squat square of cubicles piled on top of and beside each other. No guided tours are offered; there's not much to see, anyway, except for the cluttered offices of the scientist/professors who work here.

William Gray occupies one of those offices, along with a jumble of boxes containing papers that had been stored in the basement of his west Fort Collins home until it was flooded by this past summer's deluge. "They even blamed that on global warming," Gray says. He doesn't try to hide his disgust for scientists who tend to blame every weather aberration--from the Fort Collins and North Dakota floods to the impending El Nino phenomenon--on global warming.

Gray's acquaintance with global warming is a long, if intermittent, one. "I wrote a paper on it when I was in the sixth or seventh grade," he says. "That was back in the Forties, and there had been some heat waves. I don't even remember much about what I wrote--it was something I got out of Reader's Digest--and there was a war going on, so we had a lot else to be thinking about."

Gray's interest in weather was resurrected by the Korean War. When it looked like he might get drafted, he opted instead to join the Air Force, which wanted to send a few good men to school to become meteorologists. After that, Gray earned his master's and Ph.D. at the University of Chicago, in a department headed by Herbert Riehl. In 1960 Riehl founded the CSU Department of Atmospheric Sciences; a year later, he invited his protege to work for him.

Tall, white-haired and warm as the coffee he insists on making for visitors, Gray concedes he isn't the sort to change his opinions quickly. "I've been in this same office for thirty years," he says, "married to the same woman for forty years and in the same house for 32 years. Guess I'm not going anywhere."

Gray, whose official specialty is hurricanes and understanding the cycles of the oceans, admits his interest in global warming "is more of a hobby...a response to all this foolishness. For more than forty years I've been training as a meteorologist, and I felt obligated to say something when I felt that something was not right."

It isn't politically correct to question the global-warming theory, Gray cautions: "If you do, then you're 'against the environment.' If you question them, you're a 'naysayer' or a 'dissident,' or a 'contrarian,' when this is really a question of good science or bad science and what we base our decisions on."

Digging through a collection of stories describing potential global-warming disasters, he finds one that says the world's scientists have reached a consensus about the peril. "That's unprecedented," he says angrily. "Most people I know are skeptical as hell. They have all these so-called experts who aren't even in this field and don't understand the atmosphere very well, and yet they think they can make all these predictions.

"They get some Nobel Prize physicist commenting on the atmosphere...which would be like me talking about whether a nuclear accelerator should be built. I don't know about that, and neither do they know anything about how the atmosphere works--except what they've been told."

Gray's main argument is with the computer climate modelers, who "don't like me very much," he says. Although he has no problem with using computers to make five-day forecasts, "it's an outrage for them to say they can predict the future," he insists. "They haven't been able to get the past record right, or even very far in the future. But they'll talk about a hundred years down the road, 'cause nobody can prove them wrong."

As an example, Gray points to what he calls the "water vapor feedback loop." When scientists talk about global warming, they usually point to carbon dioxide as the most worrisome greenhouse gas. But that's just true in a roundabout way, Gray says.

Doubling the carbon dioxide in the atmosphere would raise the temperature only minimally in and of itself, he points out; predictions of large temperature increases of several degrees and more are based on the idea that the increased carbon dioxide will cause more water vapor--actually the major greenhouse gas--because of evaporation.

Only when computer modelers factor in water vapor as a gas that holds heat, rather than letting it escape into space, do they come up with the major warming scenarios. According to Gray, though, there's evidence that water vapor also shields the planet from sunlight, radiating that energy back into space. "It is my contention that there is no positive feedback," he says. The increase in water vapor, which holds in some heat but blocks out sunlight, effectively cancels itself out--which, he suggests, also cancels many of the global-warming predictions.

Gray has other criticisms of global warming's proponents. Modelers don't understand how the oceans work with the atmosphere, he says, and haven't been plugging the oceans' effects on cooling and heating into their equations accurately. As a result, much of what scientists are saying about global warming's impact on the number and ferocity of hurricanes is demonstrably wrong.

Although there were several particularly violent hurricanes in 1995, "there were many more hurricanes, of greater intensity, in the 1950s and 1960s," Gray points out. "They rarely note that because it doesn't fit their scenario. To the public it seems like hurricanes have gotten worse, but that's because there are more people and development in coastal areas."

As the discussion of global warming heats up, though, science often gets left behind. Gray says he's "outraged" that proponents of the theory claim their critics have been "paid off" by energy companies. Although some scientists have accepted energy-company money, those scientists were already questioning the global-warming research. "The money isn't much," he says, "$20,000 or something, which after taxes is what? $13,000. Who would sell their soul for that?

"I was approached by energy companies, but I didn't take the money. My God, I'm speaking for my own conscience. In the meantime, there's some $2 billion in government funding going to these other guys. They definitely have a vested interest in global warming being a big problem. That's how they make their living down at NCAR; they want global warming so they can get research money to study it."

After the Cold War ended and military spending on science dropped off, the scientific community needed to find "a new common enemy to support the scientific infrastructure--all those scientists and labs," Gray says. The National Science Foundation, which is NCAR's primary support, "needed to have a reason to ask for the public's money," he adds.

"And, of course, the media went along with it, because it needs a good disaster story to sell newspapers and magazines."

There are two dangers to accepting these global-warming stories as fact, Gray says. The first is that whatever treaty is worked out in Kyoto will affect industrialized nations the most, especially the United States. The U.S. produces the greatest amount of greenhouse gases, and therefore would have to make the greatest cuts to reach 1990 emissions levels, the number the IPCC panel supports. "Should we make commitments that could drastically affect our standard of living when we don't have to?" Gray asks. "It's doubtful the developing countries, which need to burn fossil fuels to catch up, will agree to any cuts...unless we're willing to subsidize them, which would lower our standard of living even further to bring them up."

The second danger concerns the integrity of science. "You can only cry wolf so often before people stop listening," Gray says.

The theory that man is the root of all evil is an old story, one that periodically resurfaces. "Centuries ago, in Spain, there was an earthquake, and the roof of a cathedral fell, killing hundreds of people," he says. "The local bishop said it was because so many of those people had sinned. It was man's fault. It's always our fault."

Challenging that view can have unappealing consequences. Colleagues at government agencies such as NOAA who have publicly questioned global-warming theories have been warned by superiors to keep their opinions to themselves, Gray says. And while he can't prove it, he believes that his recent difficulties in getting funding for his own research--even though it doesn't concern global warming--may be attributed to his own outspokenness.

So far, though, Gray's managed to continue his research and arrive at a conclusion of his own: "I believe that for the next twenty years, there will be a slight global cooling."

The three main greenhouse gases--carbon dioxide, methane and water vapor--are naturally occurring. Mother Earth produces about 200 million metric tons of carbon dioxide a year, to which man currently adds about 10 million metric tons, mostly by burning the fossil fuels oil, coal and natural gas. In the distant past, there was even more carbon dioxide in the atmosphere than there is today. But in the last forty years, scientists agree, there's been a 33 percent increase.

Without greenhouse gases, life could not survive. For one thing, plants need carbon dioxide like we need oxygen, which plants provide. For another, the planet would be too cold. When sunlight warms the Earth's surface, the surface radiates the heat back into the atmosphere, where gases absorb about 70 percent of it; the rest escapes into space.

The more gases in the atmosphere, global-warming proponents theorize, the hotter it's going to get. That's the simple explanation of the greenhouse effect that has so many scientists worried.

According to Roger Pielke, though, climate is not a simple A causes B, but rather a complex interaction of thousands of variables between the atmosphere, the oceans and land. Pielke, whose paper-strewn cubicle is a few doors down from Gray's office, says the climate modelers have failed to account for many of those variables. In particular, they don't understand the intricacies of his own specialty: the effect of land use on climate change.

Pielke says studies he conducted recently showed that evaporation of water from irrigated land around Fort Collins had a cooling effect, just like the evaporation of sweat cools a runner's body. In fact, temperatures in that area were about 8 degrees cooler than in a non-irrigated short-grass prairie area just to the east. Pielke only recently published his findings, in which he asserts that "land-use change is a major contributor to climate on a local, regional and global level."

Unlike Gray, Pielke does not doubt that man has contributed to climate change. The eastern forests that Europeans found when they came to this country are largely gone; today forests are disappearing in Africa, Asia and South America. All of that changes the climate, he says, but to what extent is still a matter of guesswork. "We're fooling ourselves if we think we can predict the future," Pielke adds.

And atmospheric scientists are going to have a particularly tough time making predictions, since they're not trained to study land surfaces. "I believe they're sincere people," Pielke says, "but they don't have the background to be making the predictions they do."

Rather than spending so much time, money and effort on something that may or may not happen in the future, Pielke believes we should focus our resources on current risks. "In Denver, would we be better off spending our money on cutting carbon dioxide emissions or carbon monoxide from automobiles?" he asks. "And elsewhere in Colorado, is it more important to put our resources toward the quality and quantity of water or questioning the right or wrong of burning of fossil fuels?"

If the Kyoto conference calls for drastic emissions cuts, he says, it's "jumping the gun. What's the bigger threat in Africa? Disease or global warming?"

As the editor of the respected Journal of Atmospheric Sciences, which publishes articles from either side of the global warming issue so long as they have been favorably reviewed by peers, Pielke says it's evident that there's no scientific consensus on global warming. Even the 1995 IPCC report, which global-warming proponents claim represents the opinion of the 2,400 scientists who participated, includes a caveat that not all of the scientists agreed with the conclusions.

"Unfortunately, there's a lot of labeling and name-calling going on," Pielke says. "The media keeps quoting the same people over and over again. Meanwhile, most of the people involved in climatology and meteorology have never been asked for their position. And because of the politics, a lot of them would now not want to talk publicly. I've talked to young scientists who say they'd be worried that their funding would be cut off."

He's experienced the censorship himself. A recent exhibit on global warming at the Denver Museum of Natural History initially included an article written by Pielke for the Christian Science Monitor--the only dissenting text in the display. But the article disappeared soon after the exhibit opened to the public.

Debate is the fuel that propels science to higher planes. The process of submitting your theory to the review, criticism and challenges of peers is the crucible through which, historically, good science must pass before it is accepted as fact. Albert Einstein developed his theory of relativity in 1905, for example, but wouldn't accept the validity of his own work for some twenty years, and not until it was proved accurate by rigorous testing.

But scientists who support the global-warming theory warn there may not be time to wait for perfect scientific consensus on the subject: Global warming could soon reach a point where even if fossil-fuel burning is curtailed, the gases already in the atmosphere would continue heating the planet.

Like many other global-warming claims, that's debatable.
Most scientists agree that the average temperature of the Earth has risen 1 degree Fahrenheit over the past century. But most of that increase occurred in the first half of the century, not the second--when fossil-fuel burning pumped up the carbon-dioxide content of the atmosphere by 33 percent.

Global-warming proponents, noting that sea levels have risen four to ten inches over the past hundred years, predict further increases, as much as several feet, which would swamp low-lying islands and coastal cities. But sea levels overall have risen 300 inches since the last Ice Age, and critics of global-warming scenarios contend that the rate of rise has not increased recently.

NOAA has detected a 20 percent increase in extreme precipitation events (hard rains, heavy snowfalls) since 1900, a trend consistent with global warming due to more water vapor in the atmosphere. But even after eighteen years of use, NASA satellites have not recorded global warming. In fact, they've noted a slight cooling trend. Global-warming proponents, who used to contend that the satellite record had not been kept long enough to give an accurate picture, now claim that satellites cannot correctly measure low-altitude warming.

Computer modelers themselves have scaled back their earlier predictions, reducing their estimates of temperature increases by one-third and sea-level rise by 25 percent. By 1995, the IPCC panel was predicting that the average temperatures would rise just 3.6 degrees by 2100. Modelers say the revisions have been made because their equipment and knowledge is stronger. But global-warming opponents, who note that the predictions have gotten milder with each generation of computer models, say the disaster mindset of policy-makers is still based on those earlier, flawed calculations.

If they base their actions on these problematic predictions, critics claim, emissions cutbacks could cost the U.S. economy billions of dollars and as many as a million jobs. Global-warming proponents, however, note that industry also made exaggerated claims about economic horrors when laws combating CFCs and acid rain were passed; those doomsday scenarios never came true. The development of energy alternatives, these proponents say, could actually stimulate the economy and create jobs.

Since the release of the 1995 IPCC report, the fight over global warming has more closely resembled an election campaign than scientific discourse.

That year, Vice President Al Gore, who's been gearing for a run as the environmentalist president, belittled scientific critics of the global-warming hypothesis. He accused a "tiny minority of dissident scientists" of treating warnings about the greenhouse effect as the "empirical equivalent of the Easter Bunny."

This past July, Secretary of the Interior Bruce Babbitt went on National Public Radio to take the offensive against global-warming naysayers. "It's an unhappy fact that the oil companies and the coal companies in the U.S. have joined in a conspiracy to hire pseudo-scientists to deny the facts and then begin raising political arguments that are essentially fraudulent," he said. "I think the energy companies need to be called to account, because what they are doing is un-American in the most basic sense."

On July 24, Clinton entered the fray by kicking off a public-relations campaign to convince the American public that something must be done--and done now--about global warming. He invited to the White House seven scientists, including three Nobel Laureates, each of whom shared apocalyptic visions of heat waves, intense storms, tropical diseases moving north, famine and oceans swamping cities. Schneider, now a professor at Stanford University, was one of the seven. This past summer's floods were an "omen," he said. "The increasing frequency and magnitude of these could very well be the first signs that the canary in the cage is starting to quiver."

"The overwhelming balance of evidence and scientific opinion is that it is no longer a theory, but now a fact, that global warming is real," Clinton concluded after the meeting. He vowed that the United States would make a commitment to "realistic and binding" carbon-dioxide-emission limits at the upcoming treaty talks in Kyoto.

"Between now and then, we have to work with the American people to get them to share that commitment," Clinton said. "We have evidence. We see the train coming; but most ordinary Americans, in their day-to-day lives, can't hear the whistle blowing."

In September Babbitt blew through Boulder, where he accused global-warming naysayers of "a campaign of misinformation and deceit...The issue is the largest, most pervasive and ominous environmental threat that we have ever confronted. It will be the dominant issue of your generation," he told several hundred CU students and faculty members.

This week Clinton is hosting another White House conference on global climate change. NCAR researcher Kevin Trenberth, who helped write the 1995 IPCC report, was one of the scientists invited to attend.

Trenberth, who was raised in New Zealand, confesses to "not having been much of a weather buff" as a boy. But after graduating college without a clear career, he went back to school and became a weather forecaster. "As such I got a lot of experience watching the weather go by, and after a time, I began to see patterns in the weather."

Those patterns are what constitute climate, and Trenberth's fascination with them led to him earning a Ph.D. from the Massachusetts Institute of Technology in atmospheric sciences; he arrived at NCAR in 1984 as an authority on El Nino. Four years later, following the tremendous heat waves and drought of 1988, the global-warming scenario really caught fire.

At the time, Trenberth was skeptical. What others were attributing to global warming, he blamed on cool water temperatures, called La Nina, in the tropical Pacific. But as he became more involved in global-warming research, he began to see the ramifications of man's production of greenhouse gases. Despite the uncertainties, he says, science as a whole points to a manmade warming trend. However, Trenberth doesn't foresee the total disaster that his friend Schneider does.

Man's affect on global warming, Trenberth suggests, will be to push weather to more extremes--extremes in all types of conditions, not just heat. The floods will be bigger floods. The droughts will last longer.

"With more evaporation, there's more water in the atmosphere, some of which will manifest itself as rain or snow," says Trenberth. While the snowfall that caused the Dakota floods last spring was not proof of global warming, he adds, "global warming could have been the straw that broke the camel's back and made it more extreme."

Citing NOAA's report that extreme precipitation events have increased, Trenberth says it's more important to learn how to deal with these events than to argue as to whether they will occur. "It may be that what were once hundred-year floods now occur every fifty or sixty years," he explains. "So we might want to examine how and when we build dikes and dams. We might want to look at the development of coastal areas."

And we should start looking right now, Trenberth cautions. The global-warming naysayers tend to be scientists who look at the little picture rather than the big one, he says, pulling out graphs that show how variable temperatures are on a daily, or monthly, or yearly basis. Those scientists are looking at the extremes of these recordings and dismissing the tiny, but steady, average increase over the past 100 years.

"What concerns me is the rate of change," Trenberth says. "Given time to adapt, we can develop technologies and mitigate any problems. My contention is that we ought to be trying to slow global warming down and give ourselves time to adjust to it."

But the proposed Kyoto treaty is flawed, he says. One problem is that developing countries won't have to agree to emissions cutbacks. While those countries argue that, per capita, American citizens use far more energy than their Asian counterparts, no one talks about the fact that there are far more Asians (or that China is one of the worst polluters, since it relies on dirty soft coal). "Population control and what it means to this whole equation has been swept under the rug," Trenberth says. "It's far too politically sensitive. But the problem will remain until it's addressed."

Rather than drastic emissions cuts, Trenberth favors small incentives to start the process--such as adding a penny a gallon every year to the gas tax in order to gently wean Americans from their gas hogs. In part because of government subsidies, American gas prices are far lower than those in Europe; when Americans realize the true cost of energy use, Trenberth says, they'll cut back--particularly if the government "maybe even makes it neutral by having a tax savings in some other area."

Industry could also be given tax incentives to become more efficient and to develop other energy sources. Such initiatives, he says, could slow global warming.

And if it occurs gradually, global warming may not be so bad after all, Trenberth suggests, risking the ire of his compatriots. "I saw a paper from Canada talking about global warming, and they were like, 'Hey, global warming...sounds great!'"

As politicians debate the issue on a global level, closer to home the discussion continues to be intensely personal.

NCAR's Mickey Glantz says he once tried to broach the subject with his colleagues of who would be winners and who would be losers if the global-warming threat were real. "But they didn't want to hear about winners," he says, "because the winners would be the people who create the most greenhouse gases and live in the northern hemisphere, which might see benefits like longer growing seasons. They didn't want to hear it...just like they don't want to hear anything the other side has to say.

"They don't pay attention to things that refute their cases," Glantz says. "They know their arguments' weaknesses and avoid talking about them. I've seen a respected scientist at NCAR throw away a letter from a colleague who challenged his theory rather than respond to it. And on this subject, you're disloyal if you don't speak with one voice."

And the global-warming naysayers are just as guilty of ignoring the evidence as are global-warming proponents, he says. "They want to say the glass of evidence is 25 percent empty rather than 75 percent full," Glantz continues.

When it comes to global warming, Glantz divides the scientific world into thirds: doves on one side, hawks on the other, and owls in the middle. "Most scientists, I believe, are owls," he says. "They may be leaning one way or the other, but the science isn't there yet. The hawks, meanwhile, have floodwaters lapping at our doors, while the doves are out there saying that more carbon dioxide will be good for plants."

And so scientists are under pressure from the public and policy-makers to give definitive answers when they don't yet exist. As a recognized authority on El Nino, Glantz is irritated by scientists who make statements to the media about what the phenomenon will mean to specific areas of the country. "I get calls from someone who wants to know how much snow he'll get in Boston because of El Nino," he says. "He's heard some scientist saying 300 inches, so now he's worried. But they don't know, and I don't know.

"We've had big El Nino years when California had a drought, and El Nino years when California was deluged with rain...a few miles either way and you get an entirely different scenario.

"The science has become irrelevant," he says. "It's politics that primes the public-policy pump.